Usefull Comands

Check Ubuntu Version

lsb_release -a

Managing packages

To update the list of possible updates:

sudo apt update

To perform the update:

sudo apt upgrade

To list installed packages:

apt list --installed

We can filter the list using the grep command.

To find the install location of a package:

dpkg -L <package>

Unfortunately, it is not possible to easily search for the user who installed the package.

To search for a package:

apt-cache search <package>

We can limit the search to check only names of the packages using the --names-only parameter.

To remove a package:

sudo apt remove <package>

Installing non-stable package versions

On Linux, the stable package versions are usually outdated, sometimes years behind the current version. To install the newer version, we have usually a few options:

  • upgrade the system: if we use an old version of the system, we can check whether the newer version is available that includes the newer package version. For more, see the Upgrade section.
  • install from source: We can manually build the package from the source and install it. See the C++ Workflow for more.
  • install package from an alternative repository: We can add an alternative repository to the system and install the package from there.

The first two options are covered in different part of this manual. Here, we focus on the third option.

To use an alternative repository, we have to a) add the repository to the system, which is a one time task, and b) install the specific package from the repository.

To add a repository, we have to:

  1. add the repository to the /etc/apt/sources.list (or to a separate file in the /etc/apt/sources.list.d/ directory). Each repository should has the line that should be added to the file on its website.
  2. sudo apt update to update the list of available packages

To install a package from the repository:

sudo apt install -t <repository> <package>

Some useful repositories

  • debian backports: the repository with the newer versions of the packages for the stable Debian version

Changing default package repositories

If the downolad speed is not satisfactory, we can change the repositories. To find the fastest repository from the list of nearby repositories, run:

curl -s http://mirrors.ubuntu.com/mirrors.txt | xargs -n1 -I {} sh -c 'echo `curl -r 0-10240000 -s -w %{speed_download} -o /dev/null {}/ls-lR.gz` {}' | sort -g -r

The number in the leftmost column indicates the bandwidth in bytes (larger number is better).

To change the repositories to the best mirror, we need to replace the mirror in etc/apt/source.list. We can do it manually, however, to prevent the mistakes, it is better to use a dedicated python script: apt-mirror-updater. Steps:

  1. install the python script: sudo pip install apt-mirror-updater
  2. backup the old file: sudo cp sources.list sources.list.bak
  3. change the mirror with the script: apt-mirror-updater -c <mirror URL>

Note that the apt-mirror-updater script can also measure the bandwidth, however, the result does not seem to be reliable.

Possible issues

The repository '<repo>' no longer has a Release file

This can happen when the repository is outdated, which can happen quickly if we use non-stable (non-LTS) versions of Ubuntu. The solution is to either:

  • change the repository to a newer one manually or
  • change the url of all repositories to http://old-releases.ubuntu.com/ubuntu/ and then upgrade the system to the newer version: bash sudo sed -i -e 's/archive.ubuntu.com\|security.ubuntu.com/old-releases.ubuntu.com/g' /etc/apt/sources.list

Upgrade

For a system upgrade, follow these steps:

  1. run the update of the current version.
  2. Then optionaly backup the WSL

  3. perform the upgrade:

    • If a) you are on a LTS version, and b) there is a new LTS version available, run sudo do-release-upgrade.
    • Otherwise, follow the steps in the next section.

  4. Ubuntu versions

Manual upgrade

For manual upgrade, follow these steps:

  1. perform steps 1 and 2 from the normal upgrade
  2. open the /etc/update-manager/release-upgrades file and set the Prompt parameter to normal or lts (depending on the desired version)
  3. backup the /etc/apt/sources.list file
  4. change the sources to the new version:
    • e.g., run sudo sed -i 's/<current version name>/<new version name>/g' /etc/apt/sources.list
  5. run a normal upgrade: sudo apt update && sudo apt upgrade
  6. finalizing the upgrade: sudo apt dist-upgrade

WSL backup

  1. check the WSL distro name: wsl -l -v
  2. shutdown WSL: wsl --shutdown
  3. backup the distro: wsl --export <disto name> <backup folder path>/<backup name>.tar